1. Field of the Invention
The present invention relates to a cleaning blade and an image forming apparatus that incorporates the cleaning blade.
2. Description of the Related Art
A conventional image forming apparatus such as a printer, a facsimile machine, or a multifunction printer performs an electrophotographic process. A charging roller uniformly charges a surface of an image bearing body or a photoconductive drum. An LED head illuminates the charged surface to form an electrostatic latent image. A developing roller develops the electrostatic latent image with toner into a toner image. A transfer roller transfers the toner image onto print paper. The toner image on the print paper is then fixed into a permanent image. Some of the toner may remain on the photoconductive drum after transfer of the toner image onto the print paper. A cleaning device removes the residual toner from the photoconductive drum.
The cleaning device includes a plate-like cleaning blade formed of an elastic material such as urethane rubber. The edge of the cleaning blade is pressed against the surface of the photoconductive drum under pressure, thereby scraping the residual toner from the surface of the photoconductive drum as the photoconductive drum rotates.
The cleaning blade is designed to have a tan δ peak temperature below −10° C., so that the residual toner may be removed sufficiently under various conditions of the environment in which the printer is installed.
A cleaning blade having a tan δ peak temperature lower than −10° C. exhibits high molecular mobility in the temperature range in which the printer is installed. Thus, the cleaning blade exhibits the properties of rubber such as elasticity, flexibility, and softness.
While the cleaning blade in a rubber state may appear to be a mere solid object, the molecules of the rubber exhibit a certain level of motion (micro-Brownian motion), still allowing the molecular chains to deform or displace to some extent.
The cleaning blade in a rubber state is easy to stretch in a direction in which the surface of the photoconductive drum rotates, so that stick-slip motion of the cleaning blade is quite active and therefore external additive comes off from the toner particles and deposits on the photoconductive drum. Further, wax contained in the toner particles elutes and adheres to the surface of the photoconductive drum, leading to filming (OPC filming) on the surface of the photoconductive drum.